H2S2014 in Kyoto: The 3rd International Conference on H2S in Biology and Medicine

Hydrogen sulfide-mediated endothelial function and the interaction with eNOS and PDE5A activity in human internal mammary arteries

Objective

To investigate the role of hydrogen sulfide (H2S) in human internal mammary arteries (IMA) and its interaction with endothelial nitric oxide synthase (eNOS) and phosphodiesterase (PDE)5A activity.

Methods

Human IMA segments from patients undergoing coronary artery bypass grafting (CABG) were studied by myography for acetylcholine and sodium hydrosulfide (NaHS)-induced relaxation. Locations of 3-mercaptopyruvate sulfurtransferase (3-MPST) and cysteine aminotransferase (CAT) were examined immunohistochemically. Levels of H2S, eNOS, phosphorylated-eNOSser1177, and PDE5A were measured.

Results

In IMA segments from 47 patients, acetylcholine-induced relaxation (resistant to NG-nitro-L-arginine and indomethacin) was significantly attenuated by aminooxyacetic acid or L-aspartate (CAT inhibitors), iberiotoxin (large-conductance calcium-activated K+ channel blocker), TRAM-34 plus apamin (intermediate- and small-conductance Ca2+-activated K+ channel blockers) or glibenclamide (ATP-sensitive K+ channel blocker). 3-MPST and mitochondrial CAT were found in endothelial and smooth muscle cells while cytosolic CAT was located only in endothelial cells. Acetylcholine significantly increased the H2S levels. The H2S donor, NaHS, increased eNOS phosphorylation and down-regulated PDE5A.

Conclusions

Human conduit artery endothelium releases H2S under basal and stimulated conditions, involving the 3-MPST/CAT pathway, eNOS phosphorylation, PDE5A activity, and potassium channels. These findings may provide new therapeutic targets for treating vasospasm in CABG grafts and facilitate the development of new vasodilator drugs.

Trend in H₂S Biology and Medicine Research-A Bibliometric Analysis

The biological and medical importance of hydrogen sulfide (H₂S) has been recognized for decades. The aim of this bibliometric study is to analyze the quantity and quality of publications in H₂S biology and medicine (H₂SBM) based on the databases of Web of Science and Google Scholar. A total of 5881 publications published between 1990 and 2016 were analyzed. The number of H₂SBM papers published before 2004 was below 100 annually, but thereafter this number rapidly increased and peaked in 2015 with more than 7-fold increase. All publications related to H₂SBM research achieved a total h-index of 136 and were cited 123,074 times. The most published disciplines in H₂S biomedicine research were the cardiovascular system (8.5%), neuroscience (6.5%), and gastroenterology hepatology (4.7%). The country with the greatest number of publications in the H₂SBM research field was the USA with 1765 (30.0%) publications, followed by China with 995 (16.9%) publications and Japan with 555 (9.4%) publications. The top 3 most published institutes were National University of Singapore, Peking University in China, and University of Groningen in Netherlands. Nitric Oxide Biology and Chemistry was the most exploited journal for H₂SBM publications with 461 articles, followed by FASEB Journal with 200 publications and Antioxidants Redox Signaling with 116 publications. The most highly cited publications and researchers in H₂SBM research were also unmasked from this bibliometric analysis. Collectively, H₂SBM publications exhibit a continuous trend of increase, reflecting the increased H₂SBM research intensity and diversity globally.

Cryogenic role of central endogenous hydrogen sulfide in the rat model of endotoxic shock

Thermoregulatory responses to lipopolysaccharide (LPS) are affected by modulators that increase (propyretic) or decrease (cryogenic) body temperature (Tb). We tested the hypothesis that central hydrogen sulfide (H₂S) acts as a thermoregulatory modulator and that H₂S production in the anteroventral preoptic region of the hypothalamus (AVPO) is increased during hypothermia and decreased during fever induced by bacterial lipopolysaccharide (LPS, 2.5mg/kg i.p.) in rats kept at an ambient temperature of 25°C. Deep Tb was recorded before and after pharmacological inhibition of the enzyme cystathionine β-synthase (CBS - responsible for H₂S endogenous production in the brain) combined or not with LPS administration. To further investigate the mechanisms responsible for these thermoregulatory adjustments, we also measured prostaglandin D₂ (PGD₂) production in the AVPO. LPS caused typical hypothermia followed by fever. Levels of AVPO H₂S were significantly increased during hypothermia when compared to both euthermic and febrile rats. Intracerebroventricular (icv) microinjection of aminooxyacetate (AOA, a CBS inhibitor; 100 pmol) neither affected Tb nor basal PGD₂ production during euthermia. In LPS-treated rats, AOA caused increased Tb values during hypothermia, along with enhanced PGD₂ production. We conclude that the gaseous messenger H₂S modulates hypothermia during endotoxic shock, acting as a cryogenic molecule.

Up Regulation of cystathione γ lyase and Hydrogen Sulphide in the Myocardium Inhibits the Progression of Isoproterenol-Caffeine Induced Left Ventricular Hypertrophy in Wistar Kyoto Rats

Hydrogen sulphide (H2S) is an emerging molecule in many cardiovascular complications but its role in left ventricular hypertrophy (LVH) is unknown. The present study explored the effect of exogenous H2S administration in the regression of LVH by modulating oxidative stress, arterial stiffness and expression of cystathione γ lyase (CSE) in the myocardium. Animals were divided into four groups: Control, LVH, Control-H2S and LVH-H2S. LVH was induced by administering isoprenaline (5mg/kg, every 72 hours, S/C) and caffeine in drinking water (62mg/L) for 2 weeks. Intraperitoneal NaHS, 56μM/kg/day for 5 weeks, was given as an H2S donor. Myocardial expression of Cystathione γ lyase (CSE) mRNA was quantified using real time polymerase chain reaction (qPCR).There was a 3 fold reduction in the expression of myocardial CSE mRNA in LVH but it was up regulated by 7 and 4 fold in the Control-H2S and LVH-H2S myocardium, respectively. Systolic blood pressure, mean arterial pressure, pulse wave velocity were reduced (all P<0.05) in LVH-H2S when compared to the LVH group. Heart, LV weight, myocardial thickness were reduced while LV internal diameter was increased (all P<0.05) in the LVH-H2S when compared to the LVH group. Exogenous administration of H2S in LVH increased superoxide dismutase, glutathione and total antioxidant capacity but significantly reduced (all P<0.05) plasma malanodialdehyde in the LVH-H2S compared to the LVH group. The renal cortical blood perfusion increased by 40% in LVH-H2S as compared to the LVH group. Exogenous administration of H2S suppressed the progression of LVH which was associated with an up regulation of myocardial CSE mRNA/ H2S and a reduction in pulse wave velocity with a blunting of systemic hemodynamic. This CSE/H2S pathway exhibits an antihypertrophic role by antagonizing the hypertrophic actions of angiotensin II(Ang II) and noradrenaline (NA) but attenuates oxidative stress and improves pulse wave velocity which helps to suppress LVH. Exogenous administration of H2S augmented the reduced renal cortical blood perfusion in the LVH state.